The invention relates to a process for the stabilization of recycled plastic mixtures, as predominantly produced in the household, in commerce and also in industry and in useful material collections, and to the stabilizer mixtures which can be used for this purpose.
Recycling of waste is a problem of increasing importance for ecological reasons. The recycling of paper, textiles, glass or metals is already carried out on a large scale, whether by separate collection or by sorting of the refuse. The recycling of plastic waste and used plastics is also an increasing aim. Thermoplastics are generally processed by re-melting.
However, the plastic waste produced in the household, in commerce or in industry or the plastic materials or used plastics obtained from collections or a return obligation, for example in specific sectors of industry, such as the automobile industry, electrical industry, agriculture or the packaging industry, predominantly comprises thermoplastics based on polyolefins, styrene polymers, polyvinyl chloride or polyethylene terephthalate.
These used plastics, which may constitute useful raw materials, can be obtained either as a single material or as a mixture.
The recycling of plastic waste frequently means the use of a mixture of different types of plastic. Known industrial separation methods, for example hydrocyclone separation, mostly give only moderately clean fractions of various plastic mixtures, for example a polyolefin mixture.
The use of plastic mixtures is associated with technical problems, since individual types of plastic have only restricted miscibility with one another, or none at all. Although various types of thermoplastics can be processed by melting and moulding, the resultant mixtures (polyblends) of immiscible plastics are inhomogeneous when considered microscopically, i.e. on a microscopic level they comprise different solid phases. This has a considerable adverse effect on the mechanical properties. Recyclates of this type can generally only be used for purposes where relatively low strength requirements are made, for example as fillers or where thick-walled parts are used, for example noise protection dams.
Typical incompatible combinations which occur in domestic refuse are, for example, polyethylene and PVC or polyethylene and polystyrene or PET and polyolefins. In order to solve this problem, it has been proposed to add polymeric compatibilizers, also known as solid phase dispersants. Thus, for example, the addition of chlorinated polyethylene is capable of homogenizing mixtures of polyethylene and PVC. The addition of styrene-butadiene copolymers is capable of homogenizing mixtures of polyolefins and polystyrene. As a result of such a homogenization, the mechanical properties improve so much that these polyblends are also suitable for high-performance uses. A review of these developments is given by C. Sadrmohaghegh, G. Scott and E. Setudeh in Polym. Plast. Technol. Eng. 24 (1985), 149-185.
In an article which appeared in Polymer Eng. and Science, Vol. 17, pp. 700-705 (1977), the effect of small amounts of PVC and CPE on recycled polyethylene is studied, the authors observing that satisfactory stabilization of such recyclates is still not possible.
For the stabilization of recycled high-density polyethylene, P. Vink, R. T. Rotteveel and J. D. M. Wisse in Polymer Degr. and Stability, Issue 9, p. 133 (1984) studied various stabilizers from the classes of the phosphites, hindered phenols, benzotriazoles, hindered amines and phosphonites.
These authors also indicated that the recyclates must be re-stabilized Although the plastics have mostly been treated originally with stabilizers against thermooxidative and in some cases also against photooxidative degradation, these stabilizers are lost during use of the plastics, during storage of the waste and during processing of the recyclates, in some cases due to migration, extraction or by degradation. In addition, a recycled plastic generally differs structurally and also chemically from a new plastic as a consequence of the prior use or due to storage and processing; for example, sites of attack for oxidative degradation may already have formed. A recycled plastic therefore requires, for example, a relatively large amount of stabilizers or alternatively stabilizers which take into account these particular circumstances. The difficulty of finding suitable stabilizers is due to the specific type of previous damage/impurities, which may have taken place over an extended period.
Stabilization of a plastic mixture is also a difficult task, since each type of polymer makes specific requirements of the stabilizers. Thus, for example, completely different stabilizers are used for vinyl chloride polymers than for polyolefins or styrene polymers.
It would therefore be necessary to add a mixture of various stabilizers in order to stabilize a plastic mixture. In the case of complex plastic mixtures, this is a complicated method. In addition, various stabilizers can have adverse effects on one another or a stabilizer for one component can be damaging for the other component.
This problem has also been studied in the abovementioned literature and in Europ. Polym. J. 18 (1982), 1007, and the authors come to the conclusion that certain nickel complexes, in particular nickel dialkyldithiocarbamates, effect the best stabilization both against thermooxidative and against photooxidative degradation of polyethylene/polystyrene and polyethylene/polypropylene blends which have been homogenized by means of a compatibilizer. There is no mention therein of the stabilization of recyclates also containing PVC or of complex recyclate mixtures.
From U.S. Pat. No. 4,443,572, JP-A-57-202,346, JP-A-01/020,249 and FR-A-2 528 056 it is known to use a mixture including a phenol, a pentaerythritol diphosphite and a selected inorganic compound in certain virgin plastics.
It has now been found that mixed recycled plastics can be stabilized in a simple and economical manner against thermooxidative degradation during processing and subsequent use by means of a mixture of stabilizers known per se.
The invention relates to a process for the stabilization of mixtures of recycled plastics, predominantly thermoplastics, obtained from domestic, commercial and industrial waste or from useful material collections, which comprises adding from 0.01 to 15% by weight of a mixture of a) at least one sterically hindered phenol, b) at least one organic phosphite or phosphonite and c) at least one inorganic compound from the series consisting of metal oxides, hydroxides and carbonates to these plastics.
The a:b weight ratio is preferably from 20:1 to 1:20, particularly preferably from 10:1 to 1:1:10, very particularly preferably from 4:1 to 1:4. The (a+b):c weight ratio is preferably from 10:1 to 1:20, particularly preferably from 5:1 to 1:10, very particularly preferably from 3:1 to 1:3.
The plastic mixtures to be stabilized are, for example, used plastics from households and commerce (for example supermarkets), which predominantly originate from packaging materials. These can be, for example, films, bags, bottles and other containers or foams. Other materials may also be present. However, it is also possible for mixtures of plastics which have been previously damaged by use, storage or processing to be stabilized. These materials originate, for example, from useful material collections or return obligations, for example from the automobile industry, electrical/electronic industry, construction, agriculture and the textile industry.
The invention therefore relates to the stabilization of recycled plastic mixtures of this type which comprise 25-100% by weight, in particular 35-99% by weight, of polyolefins, 0-25% by weight of polystyrene, 0-25% by weight of polyvinyl chloride and 0-25% by weight of other thermoplastics, it also being possible for mixtures to be present within these groups of thermoplastics. Non-thermoplastics may also be present in the mixture in small amounts.
In particular, the invention relates to the stabilization of recycled plastic mixtures of this type which comprise 55-95% by weight of polyolefins, 5-25% by weight of polystyrene, 0-15% by weight of polyvinyl chloride and 0-10% by weight of other thermoplastics.
Also preferred are recycled mixtures of polyethylene and polypropylene.
In plastic mixtures, the dominant polyolefins are usual polyethylene (PE) and polypropylene (PP), in particular low-density polyethylene (UDPE), linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), furthermore copolymers such as ethylene-propylene (EPM) and ethylene-propylene-diene (EPDM) copolymers and ULDPE-MDPE. Polystyrene (PS and EPS) is also taken to mean copolymers containing styrene (for example ABS, ASA, HIPS and IPS), and polyvinyl chloride (PVC) is also taken to mean copolymers predominanty comprising vinyl chloride (for example CPE). Of other thermoplastics, useful material collections principally contain polyethylene terephthalate (PET), and in addition polyamides, polycarbonate, cellulose acetate and polyvinylidene chloride. Secondary amounts, up to about 5%, of non-thermoplastics, for example polyurethanes, formaldehyde resins and phenolic resins, and typical amino resins, and also elastomers, for example vulcanized or unvulcanized rubber, may also be present. In certain plastic wastes, small amounts of foreign substances, for example paper, pigments and adhesives, which are frequently difficult to remove, may also be present. These foreign substances may also originate from contact with diverse substances during use or processing, for example fuel residues, paint components, traces of metal, initiator residues or traces of water.
From 0.05 to 5% by weight of the mixture of a, b and c are preferably added to the recyclate. From 0.1 to 2% by weight of the mixture of a, b and c are particularly preferably added. From 0.1 to 1% by weight is very particularly preferably added
The sterically hindered phenols used as component a are known stabilizers against thermooxidative ageing of plastics, in particular polyolefins. These compounds preferably contain at least one group of the formula 
in which
Rxe2x80x2 is hydrogen, methyl or tert-butyl, and
Rxe2x80x3 is substituted or unsubstituted alkyl or substituted or unsubstituted thioether.
Examples of sterically hindered phenols of this type are:
2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-i-butylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(xcex1-methylcyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, 2,6-dinonyl-4-methylphenol, 2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol, 2,2xe2x80x2-thiobis(6-tert-butyl-4-methylphenol), 2,2xe2x80x2-thiobis(4-octylphenol), 4,4xe2x80x2-thiobis(6-tert-butyl-3-methylphenol), 4,4xe2x80x2-thiobis(6tert-butyl-2-methylphenol), 2,2xe2x80x2-methylenebis(6-tert-butyl-4-methylphenol), 2,2xe2x80x2-methylenebis(6-tert-butyl-4-ethyphenol), 2,2xe2x80x2-methylenebis[4-methyl-6-(xcex1-methylcyclohexyl)phenol], 2,2xe2x80x2-methylenebis(4-methyl-6-cyclohexylphenol), 2,2xe2x80x2-methylenebis(6-nonyl-4-methylphenol), 2,2xe2x80x2-methylenebis(4,6-di-tert-butylphenol), 2,2xe2x80x2-ethylidenebis(4,6-di-tert-butylphenol), 2,2xe2x80x2-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2xe2x80x2-methylenebis[6-(xcex1-methylbenzyl)-4-nonylphenol], 2,2xe2x80x2-methylenebis[6-(xcex1,xcex1dimethylbenzyl)-4-nonyl-phenol], 4,4xe2x80x2-methylenebis(2,6-di-tert-butylphenol), 4,4xe2x80x2-methylenebis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-3-n-do-decylmercaptobutane, ethylene glycol bis[3,3-bis(3xe2x80x2-tert-butyl-4xe2x80x2-hydroxyphenyl)butyrate], bis(3-tert-butyl-4-hydroxy-5-methylphenyl)dicyclopentadiene, bis[2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethyl benzene, bis(3,5-di-tert-butyl-4hydroxybenzyl)sulfide, isooctyl 3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate, bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, dioctadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate and the calcium salt of monoethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate.
Component a is particularly preferably a compound containing at least one group of the formula 
in which
Rxe2x80x2 is methyl or tert-butyl; and
Rxe2x80x3 is substituted or unsubstituted alkyl or substituted or unsubstituted thioether.
Examples of such hindered phenols are the esters of xcex2-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and of xcex2-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with monohydric or polyhydric alcohols, for example with methanol, octadecanol, 1,6-hexanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,Nxe2x80x2-bis(hydroxyethyl)oxalamide, and the amides of these acids, for example N,Nxe2x80x2-bis(3,5-di-tert-butyl-4-hydroxyphenyl-propionyl)hexamethylenediamine, N,Nxe2x80x2-bis(3,5-di-tert-butyl-4-hydroxyphenyl-propionyl)trimethylenediamine and N,Nxe2x80x2-bis(3,5-di-tert-butyl-4-hydroxyphenyl-propionyl)hydrazine.
Also particularly preferred are the following compounds: 
{2-(1,1-dimethylethyl)-6[[3-(1,1-dimethylethyl)-2-hydroxy-5-methylphenyl]-methyl]-4-methylphenyl 2-propenoate}; 
{benzenepropanoic acid 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-1,6hexanediylester}; 
{benzenepropanoic acid 3-(1,1-dimethylethyl)-4-hydroxy-5-methyl-1,2-ethanediylbis(oxy-2,1-ethanediyl)ester}; 
{2-methyl-4,6-bis[(octylthio)methyl]phenol)}; 
{2,2xe2x80x2-ethylidene-bis-(4,6-di-tert.butylphenol)}; 
{benzenepropanoic acid 3,5-bis(1,1-dimethylethyl)-4-hydroxy-thiodi-2,1-ethanediylester}; 
{4,4xe2x80x2,4xe2x80x3-[(2,4,6-trimethyl-1,3,5-benzenetriyl)tris(methylene)]tris[2,6-bis(1,1-dimethylethyl)phenol}; 
{1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione}.
Component a is most preferably a pentaerythritol ester or octadecyl ester of xcex2-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid or 2,2xe2x80x2-ethylidenebis(4,6-di-tert-butyl-phenol).
The organic phosphites and phosphonites used as component b are likewise known as stabilizers for plastics. They are used, in particular, as processing stabilizers for polyolefins.
They are predominantly aromatic phosphites and phosphonites, for example triphenyl phosphite, diphenyl alkyl phosphites, trictadecyl phosphite, phenyl dialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, distearyl pentaerythrityl diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, distearyl pentaerythrityl diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythrityl diphosphite, tristearyl sorbityl triphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4xe2x80x2-biphenylene diphosphonite, 3,9-bis(2,4-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-tris(2,4,6-tis-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane and 2,2xe2x80x2-ethylidenebis(4,6-di-tert-butylphenyl)fluorophosphite.
Preferred compounds are
tris-(2,4-di-tert.butylphenyl)phosphite; 
Component b is particularly preferably tris(2,4-di-tert-butylphenyl)phosphite.
Component c is an inorganic compound from the series consisting of metal oxides, hydroxides and carbonates.
These are in particular metal oxides, hydroxides or carbonates of elements from main group II or sub-group II, IV or VII. Preference is given to calcium, magnesium, zinc, titanium and manganese as metals, the oxides being particularly preferred, such as CaO MgO, ZnO, TiO2, MnO2 and very particularly calcium, magnesium and zinc oxide. Calcium oxide is most preferred.
It is also possible to use a mixture of various compounds for components a, b and c. For example, component c can be a mixture of calcium oxide and calcium carbonate.
An example which may be given of a metal hydroxide is magnesium hydroxide, and an example which may be given of a metal carbonate is calcium carbonate. It is also possible to use salts with different anions, for example magnesium aluminium hydroxycarbonates, known as hydrotalcites.
Other suitable stabilizers from the series consisting of the lactates, for example calcium lactate or calcium stearoyl-2-lactylate, or lactones, for example 
may additionally be added.
The present invention furthermore relates to stabilizer mixtures and to the use thereof for the stabilization of recycled mixtures of plastics, predominantly thermoplastics, obtained from domestic, commercial and industrial waste or useful material collections, these stabilizer mixtures comprising a) at least one sterically hindered phenol, b) at least one organic phosphite or phosphonite and c) at least one inorganic compound from the series consisting of metal oxides, hydroxides and carbonates.
Paricularly preferred stabilizer mixtures comprise per 100 parts (by weight)
(A) as component a) 5-50 parts of the pentaerythrityl ester of xcex2-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, as component b) 5-50 parts of tris-(2,4-di-tert-butylphenyl)phosphite and as component c) 5-90 parts of calcium oxide;
(B) as component a) 5-50 parts of the octadecyl ester of xcex2-(3,5-di-tert-butyl-4-hydroxy-phenyl)propionic acid, as component b) 5-50 parts of tris-(2,4-di-tert-butylphenyl)phosphite and as component c) 5-90 parts of calcium oxide;
(C) as component a) 5-50 parts of 2,2xe2x80x2-ethyliden-bis-(4,6-di-tert-butylphenol), as component b) 5-50 parts of tris-(2,4-di-tert-butylphenyl)phosphite and as component c) 5-90 parts of calcium oxide;
(D) as component a) 10-30 parts of the octadecyl ester of xcex2-(3,5--tert-butyl-4-hydroxy-phenyl)propionic acid, as component b) 10-30 parts of tris-(2,4-di-tert-butylphenyl)phosphite and as component c) 30-70 parts of calcium oxide; or
(E) as component a) 5-30 parts of the octadecyl ester of xcex2-(3,5-di-tert-butyl-4-hydroxy-phenyl)propionic acid, as component b) 5-30 parts of tris-(2,4-di-tert-butylphenyl) phosphite, as component c) 540 parts of calcium oxide, as well as 10-50 parts of calcium stearate.
The present invention furthermore relates to recycled mixtures of plastics, predominantly thermoplastics, obtained from domestic, commercial and industrial waste or useful material collections, these recycled mixtures comprising a) at least one sterically hindered phenol, b) at least one organic phosphite or phosphonite and c) at least one inorganic compound from the series consisting of metal oxides, hydroxides and carbonates.
Preferred recycled mixtures of plastics, predominantly thermoplastics, preferred stabilizer mixtures and their use conform in their components and mixing ratios to the preferences described in greater detail under the process.
The addition of these combinations to the recyclate allows thermoplastic processing with reduced degradation and/or extends the service life of the materials produced from the recyclate. This is true irrespective of whether a compatibilizer is added to the recyclate or not. However, the addition of the combination of a, b and c is of particular significance for recyclates to which is added a polymer or polymer mixture which increases the compatibility of the individual plastics with one another, since this polymer generally also requires stabilization.
Further conventional plastic additives can also be polymers which improve the material properties of the previously damaged plastic, for example elastomers (impact modifiers) and compatibilizers. Impact modifiers are homopolymers or copolymers which are able to modify brittle polymers so that they remain tough even at low temperatures. EP(D)M polymers, ABR, BR and SBR graft polymers, inter alia, are suitable for this purpose.
The compatibilizers can be, for example, copolymers, in particular block copolymers, of styrene with butadiene and, if desired, acrylonitrile. They can be copolymers of ethylene and propylene, and may contain a third monomer component, for example butadiene.
Chlorinated polyethylene or ethylene-vinyl acetate copolymers are also suitable as compatibilizers, naturally depending on the particular composition of the recyclate.
Further suitable compatibilizers contain, in particular, polar groups, e.g. maleic anhydride-styrene copolymers or graft polymers containing acrylic acid groups, maleic anhydride groups or glycidyl groups.
These polymeric compatibilizers are generally used in amounts of 2-20% by weight, based on the plastic mixture.
The stabilizing action of the mixture of a, b and c, in particular the long-term stability, may be synergistically increased, if desired, by the addition of so-called thiosynergists. These are aliphatic thioethers, in particular esters of thiodipropionic acid. Examples are the lauryl, stearyl, myristyl and tridecyl esters of thiodipropionic acid or distearyl disulfide. These thiosynergists are preferably used in an amount of from 0.1 to 1% by weight, based on the recyclate.
If high light stability is also required of the article produced from the recyclate, the addition of one or more light stabilizers is advisable. Suitable light stabilizers are, in particular, those from the series consisting of the benzophenones, benzotriazoles, oxanilides and sterically hindered amines. Examples of such compounds are:
2.1. 2-(2xe2x80x2-Hydroxyphenyl)benzotriazoles, for example 2-(2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole, 2-(3xe2x80x2,5xe2x80x2-di-tert-butyl-2xe2x80x2-hydroxyphenyl)benzotriazole, 2-(5xe2x80x2-tert-butyl-2xe2x80x2-hydroxyphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-5xe2x80x2-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3xe2x80x2,5xe2x80x2-di-tert-butyl-2xe2x80x2-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-tert-butyl-2-hydroxy-5xe2x80x2-methylphenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-sec-butyl-5xe2x80x2-tert-butyl-2xe2x80x2-hydroxyphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-4xe2x80x2-octyloxyphenyl)benzotriazole, 2-(3xe2x80x2,5xe2x80x2-di-tert-amyl-2xe2x80x2-hydroxyphenyl)benzotriazole, 2-(3xe2x80x2,5xe2x80x2-bis-(xcex1,xcex1-dimethylbenzyl)-2xe2x80x2-hydroxyphenyl)benzotriazole, mixture of 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-tert-butyl-5xe2x80x2-[2-(2-ethylhexyloxy)-carbonylethyl]-2xe2x80x2-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-methoxycarbonylethyl)phenyl)benzotriazole, 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-octyloxycarbonylethtyl)phenyl)benzotriazole, 2-(3xe2x80x2-tert-butyl-5xe2x80x2-[2-(2-ethylhexyloxy)carbonylethyl]-2xe2x80x2-hydroxyphenyl)benzotriazole, 2-(3xe2x80x2-dodecyl-2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole, and 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-isooctyloxycarbonylethyl)phenylbenzotriazole, 2,2xe2x80x2-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazole-2-ylphenol]; the transesterification product of 2-[3xe2x80x2-tert-butyl-5xe2x80x2-(2-methoxycarbonylethyl)-2xe2x80x2-hydroxyphenyl]-2H-benzotriazole with polyethylene glycol 300; [Rxe2x80x94CH2CH2xe2x80x94COO(CH2)3]2, where R=3xe2x80x2-tert-butyl-4xe2x80x2-hydroxy-5xe2x80x2-2H-benzotriazol-2-ylphenyl.
2.2. 2-Hydroxybenzophenones, for example the 4hydroxy, 4-methoxy, 4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2xe2x80x2,4xe2x80x2-trihydroxy and 2xe2x80x2-hydroxy-4,4xe2x80x2-dimethoxy derivatives.
2.3. Esters of substituted and unsubstituted benzoic acids, as for example 4-tertbutylphenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoyl resorcinol, bis(4-tert-butylbenzoyl)resorcinol, benzoyl resorcinol, 2,4-di-tertbutylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate. benzoate.
2.4. Acrylates, for example ethyl xcex1-cyano-xcex2,xcex2-diphenylacrylate, isooctyl xcex1-cyano-xcex2,xcex2-di-phenylacrylate, methyl xcex1-carbomethoxycinnamate, methyl xcex1-cyano-xcex2-methyl-p-methoxy-cinnamate, butyl xcex1-cyano-xcex2-methyl-p-methoxy-cinnamate, methyl xcex1-carbomethoxy-p-methoxycinnamate and N-(xcex2-carbomethoxy-xcex2-cyanovinyl)-2-methylindoline.
2.5. Nickel compounds, for example nickel complexes of 2,2xe2x80x2-thio-bis-[4-(1,1,3,3-tetra-methylbutyl) phenol], such as the 1:1 or 1:2 complex, with or without additional ligands such as n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickel salts of the monoalkyl esters, e.g. the methyl or ethyl ester, of 4-hydroxy-3,5-di-tert-butylbenzylphosphonic acid, nickel complexes of ketoximes, e.g. of 2-hydroxy-4-methylphenyl undecylketoxime, nickel complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without additional ligands.
2.6. Sterically hindered amines, for example bis(2,2,6,6-tetramethyl-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-piperidyl)succinate, bis(1,2,2,6,6-pentamethylpiperidyl)sebacate, bis(1,2,2,6,6-pentamethylpiperidyl)n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the condensate of N,Nxe2x80x2-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1,3,5-triazine, tris(2,2,6,6-tetramethyl piperidyl)nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, 1,1xe2x80x2-(1,2-ethanediyl)bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, bis(1,2,2,6,6pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate, 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazasprio[4.5]decan-2,4-dion, bis(1-octyloxy-2,2,6,6-tetra-methylpiperidyl) sebacate, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate, the condensate of N,Nxe2x80x2-bis-(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of 2-chloro-4,6-bis(4-n-butyl-amino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane, the condensate of 2-chloro-4,6-di-(4n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine and 1,2-bis-(3-aminopropylamino)ethane, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione, 3-dodecyl-1-(2,2,6,6tetramethyl-4-piperidyl) pyrrolidin-2,5-dione, 3-dodecyl-1-(1,2,2,6,6-pentamethylpiperidyl)pyrrolidine-2,5-dione and polysiloxanes containing 2,2,6,6-tetramethyl-4-piperidyl groups.
2.7. Oxamides, for example 4,4xe2x80x2-dioctyloxyoxanilide, 2,2xe2x80x2-dioctyloxy-5,5xe2x80x2-di-tert-butoxanilide, 2,2xe2x80x2-didodecyloxy-5,5xe2x80x2-di-tert-butoxanilide, 2-ethoxy-2xe2x80x2-ethoxanilide, N,Nxe2x80x2-bis(3-methylaminopropyl)oxamide, 2-ethoxy-5-tert-butyl-2xe2x80x2-ethoxanilide and its mixture with 2-ethoxy-2xe2x80x2-ethyl-5,4xe2x80x2-di-tert-butoxanilide and mixtures of ortho- and para-methoxy-disubstituted oxanilides and mixtures of o- and p-ethoxy-disubstituted oxanilides.
2.8. 2-(2-Hydroxyphenyl)-1,3,5-triazines, for example 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3, 5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxphenyl)-4,6-bis(4-methylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2hydroxy-3-butyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxy-propyloxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-triazine.
The light stabilizers are preferably added in an amount of from 0.01 to 2% by weight, in particular from 0.05 to 0.5% by weight, based on the plastic mixture. The light stabilizer used is preferably a combination of a benzotriazole with a sterically hindered amine.
The stabilizer mixtures according to the invention containing, if desired, the additives mentioned can be employed in compact or extruded form or on a support material, or added directly, as a mixture or in the form of powders, to the recyclate.
If required, further conventional plastic additives can be added to the recycled plastic mixture, for example fillers, such as sawdust or mica, reinforcing agents, such as glass fibres, glass beads or mineral fibres, pigments, plasticizers, lubricants, such as metal stearates or laurates, flameproofing agents, antistatics or blowing agents. These additives depend on the intended use of the recyclate. In a preferred embodiment, the lubricant used is calcium or zinc stearate or a mixture thereof.
The recyclates stabilized in this way can be used for a very wide variety of applications, for example for tubes, profiles, sheets, cable insulations, sports equipment, garden furniture, films, construction parts, parts of vehicles and machines and containers of all types, for example bottles.
The recyclate can also be mixed with new plastics or employed together with new plastics, for example in a coextrusion process.
The examples below illustrate the novel process and stabilizer mixture in greater detail. As in the remainder of the description, parts are parts by weight and percentages are per cent by weight, unless otherwise stated.